Machine tools utilizing a rotating workpiece or a rotating spindle are often capable of permitting sequential tool operation on the workpiece. For instance, where the workpiece is rotating such as in lathes, turret lathes and chucking machines, a variety of tools such as boring tools, centers, drills and reamers may be mounted upon an indexable tool holder, such as a turret, for sequential engagement with the workpiece. In this manner a plurality of machining operations may be accomplished without tranfer of the workpiece to another station or rotating chuck or spindle, but the nature of the machining operations are limited.
Machine tools utilizing rotating tools such as drills and boring bits, may be mounted upon rotatable spindles of the axially translatable type. Such tools normally require that the workpiece be retrieved from a supply, chucked into the workpiece holder, machined by the tools, unchucked, and placed in a bulk container for transfer to the next machine tool. Such extensive multiple handling of the workpiece is expensive and time consuming, and makes it difficult to insure high accuracy and quality.
Conventional machine tools do not permit the ready machining of opposite sides of a workpiece. For instance, workpieces such as hubs, blanks and gears often require turning and drilling operations on opposite sides thereof, and such operations require that the workpiece be chucked, machined, unchucked and then transported to another machine wherein the workpiece opposite side is chucked permitting machining of the side not previously accessible. The operations on opposite sides of the part have required two separate machines and two chuckings.
It is an object of the invention to provide a machine tool of the automated type wherein the workpiece is sequentially transferred from one work station to another, each station utilizing a linearly displaceable rotating work-holding spindle wherein sequential operations may be automatically achieved upon a common workpiece.
Another object of the invention is to provide a machine tool having a base and a transfer region defined thereon wherein workpieces are sequentially transferred between adjacent aligned rotating spindles permitting sequential secondary operations to be automatically performed on the workpiece.
A further object of the invention is to provide a machine tool of the multiple spindle type wherein the base of the machine tool includes a central region and lateral sides disposed on opposite sides of the transfer central region. Tools located on opposite sides of the central region permit the workpiece to be automatically sequentially machined on opposite sides thereby minimizing handling and material flow problems.
In the practice of the invention, a machine tool includes a heavy base having a central region and lateral sides located on opposite sides of the central region. In most cases, the base will be of an elongated configuration, and preferably, the base includes a plurality of laterally extending portions having a length perpendicularly disposed to the length of the central region.
A plurality of work-holding spindles are mounted upon the base lateral sides, a single spindle usually being located upon each lateral portion, and preferably, spindles are located upon each base lateral side with respect to the central region. The spindles consist of elongated tubular heads mounted to be displaceable in their longitudinal direction, and each head usually includes a rotating work-holding spindle powered by an electric motor. However, non-rotating spindles may also be used at selected locations. Longitudinal displacement of the spindles is provided by a linear actuator, such as a threaded shaft or rod rotated by an electric motor. Work-holding means are mounted upon one end of the spindle, while torque transmitting means are defined upon the other spindle end in operative engagement with the spindle drive motor.
The heads move in a direction substantially perpendicular to the length of the machine tool base central region, and work transfer apparatus is mounted upon the base central region for sequentially transferring workpieces between adjacent spindles. Preferably, the transfer means includes a plurality of work-holding blocks reciprocal between alignment with adjacent spindles in the direction of the central region length.
As the spindles are mounted upon opposite sides of the workpiece transfer apparatus, the workpieces may be machined upon opposite sides by tools located adjacent the spindles as they are transferred between adjacent spindles, and the workpiece is sequentially transferred along the length of the machine tool central region to complete the desired operations.
The work transfer apparatus includes an elongated beam suspended above the base central region, and the workpiece blocks suspend below this beam whereby the blocks may be readily aligned with the spindles. Reciprocal motor means, such as of the hydraulic or screw actuator type, are used to reciprocate the beam and workpiece holders.
The apparatus of the invention permits a series of machining operations to be produced on a workpiece, the operation of the machine tool is fully automated, and the concise configuration of the machine tool and the rapid sequential machining operations permits relatively complex machining to be rapidly produced.